In the charging and discharging process of new energy vehicles, how to maintain power battery within optimum operating temperature range, reduce the peak temperature and temperature difference, which is a problem needs to be paid attention to. Proper cooling technology can reduce the negative influence of temperature on battery pack, effectively improve power battery efficiency, improve the safety in use, reduce the aging rate, and extend its service life. In this context, several battery thermal management systems(BTMS) are reviewed, including air cooling BTMS, liquid cooling BTMS and refrigerant direct cooling BTMS in traditional battery thermal management system; phase change material-based BTMS, heat pipe-based BTMS and thermoelectric element-based BTMS in new battery thermal management system. In order to reduce negative influence of excessive temperature on the battery pack, and to seek feasible solutions for BTMS in future development, the above six power battery cooling technologies are discussed. Summarize the research emphases and research progress of different BTMS at present. Objectively evaluate the advantages and disadvantages of each BTMS. Considering actual working conditions, the installation feasibility, as well as economic benefits of each BTMS, then discuss proper solutions, and predict future development trends reasonably. Finally, analyze and discuss the differences and gaps between traditional and new BTMS. Providing a reference for designing the best BYMS solution. Ensuring the battery is in the optimum operating temperature range, maintain the BTMS stable operation, and improve battery conversion efficiency, providing valuable solutions for the BTMS research in the future.

Research progress on power battery cooling technology for electric vehicles

Thermal energy storage using phase change materials (PCM) proved to be a promising technology because of its relative advantages over the other types of energy storage methods. Along with thermophysical properties of PCM, the performance of latent heat based thermal energy storage system depends on the design of the heat exchanger. Although extensive research is being carried out over the past few years, an integrated study on the design of PCM heat exchanger is scarce. This review presents the in-depth analysis of various operating conditions and design parameters that need to be considered in the design of a PCM based heat exchanger. Shell and tube type, triple concentric tube type heat exchangers are discussed along with the various heat transfer techniques employed in both the types of heat exchangers. In each enhancement technique, the influencing geometric parameters are summarized, and the recommended values of those parameters are provided. The present article is expected to be a helpful reference for the researchers working in the field of thermal energy storage.

Influence of operational and design parameters on the performance of a PCM based heat exchanger for thermal energy storage – A review

Proton exchange membrane fuel cell (PEMFC) vehicles (PEMFCV) have drawn tremendous attention owing to the advantages of low or zero emissions. Effective integrated thermal management systems (ITMS) considering thermal loops coupling and interaction and with a rational strategy are crucial for the efficient and secure operation of PEMFCV. Therefore, ITMS in PEMFCV are worthy to be reviewed comprehensively. This paper aims to provide the general and current ideas of ITMS design in PEMFCV from part-level to system-level, along with control strategies. The factors that affect the thermal performance of heat-generating components and systems are deeply analysed, and the key findings, challenges, and future work are presented. It is found that liquid cooling is more appropriate for ITMS because of the high specific heat and the convenience of integrating other thermal systems, and that heat pumps tend to be a more suitable choice for air conditioning systems. The future work mainly includes the improvement of cooling and cold start of PEMFC, perfection and verification of waste heat recovery system, exploration of new air conditioning systems, integration of systems, coupling of ITMS and energy management systems, and enhancement of model accuracy. The provided information is useful to guide the system layout and control strategies for ITMS at the early design stage. 

Progress and perspectives of integrated thermal management systems in PEM fuel cell vehicles: A review

Advanced high temperature heat pump configurations using low GWP refrigerants for industrial waste heat recovery: A comprehensive study

Life cycle energy, emissions and cost evaluation of CO2 air source heat pump system to replace traditional heating methods for residential heating in China: System configurations

The air conditioning (AC) system provides cool, heating and ventilation in the cabin of the electric vehicles (EVs). It is necessary to control the interior thermal environments of the vehicle and ensure safety in visibility. Because AC systems are electrically powered, vehicle range is reduced drastically when the AC system is operating. EVs present a particular challenge to the development of more efficient AC systems for automotive applications. In this paper, the state of the art for various AC system solutions to EVs was critically reviewed. The investigations of alternative solutions are continuing along many parallel routes, e.g. vapor compression refrigeration-dedicated heater AC systems, reversible vapor compression heat pump AC systems, non-vapor compression AC systems and integrated thermal management system combined AC and battery pack. The characteristics and particular applications of each solution have been extensively discussed. Finally, a comparison listing the various pros and cons of the different available solutions was presented.

The solutions to electric vehicle air conditioning systems: A review

Progress in ejector-expansion vapor compression refrigeration and heat pump systems

The transcritical CO2 two-phase flow in the ejector was investigated numerically by the computational fluid dynamics (CFD) method. The accuracy of the built three-dimensional CFD model was validated by contrasting the simulating results with the available experimental data in the literature. The distribution of pressure, velocity and two-phase volume fraction inside the ejector was analyzed. The effect of the primary nozzle diverging angle on the performance of the ejector was obtained. The results showed that the pressure of the CO2 is decreased and the velocity is increased after the stream enters the primary nozzle. The velocity at the exit of the primary nozzle reaches a maximum value, which is about 168 m/s. The two streams are then mixed in the mixing chamber; the velocity and the pressure were found to be shocked initially and then tend to be stable. The velocity decreases and the pressure increases gradually in the diffuser section. The vaporization of the transcritical CO2 was found to be occurred near the throat of the primary nozzle. The optimum diffusion angle of the primary nozzle was found to be about 6°, where the mass entrainment ratio is 0.83.

Xu Feng

Papers

The solutions to electric vehicle air conditioning systems: A review

Progress in ejector-expansion vapor compression refrigeration and heat pump systems

Numerical Study on Two-Phase Flow of Transcritical CO2 in Ejector

A Parametric Study on the Effect of Mixing Chamber for Expansion Work Recovery CO2 Ejector